Institute for Systems Research

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Author: search.filters.author.Tsai, L-W.Subject: search.filters.subject.optimization

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    Multiobjective Optimization of a Leg Mechanism with Various Spring Configurations for Force Reduction
    (1996) Shieh, W-B.; Azarm, Shapour; Tsai, L-W.; Tits, A.L.; ISR
    In this paper, the design of a two degree-of-freedom leg mechanism is accomplished by a two-stage optimization process. In the first stage, leg dimensions are optimized with respect to three design objectives: minimize (i) leg size, (ii) vertical actuating force, and (iii) peak crank torque for an entire walking cycle. Following the optimization of leg dimensions, in the second stage, spring elements with various placement configurations are considered for further reduction of the actuating force and crank torque. Several tradeoff solutions are obtained and a comparison between variously spring configurations is made. It is shown that the inclusion of spring elements can significantly reduce the actuating force and crank torque.
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    A CAD System for the Optimization of Gear Ratios for Automotive Automatic Transmissions
    (1992) Mogalapalli, Srinivas N.; Magrab, Edward B.; Tsai, L-W.; ISR
    An interactive design system has been developed for the design of automatic automotive transmission gear trains that can provide at least three forward and one reverse speed ratios. This user- friendly windowing system can access help files, display the functional representation of a mechanism, optimize the gear ratios and present the numerical results. The optimization procedure to find the optimum gear ratios and the corresponding number of gear teeth uses the Augmented Lagrangian Multiplier Method and can be applied to all epicyclic gear trains having two sets of three gears in which a ring gear is connected to a sun gear through a planetary gear. The Simpson and General Motors THM 440 gear trains are used to demonstrate the methodology. The gear teeth combinations are found such that they achieve the optimized gear ratios to within ﯠ1% and satisfy the geometric constraints. PHIGS graphics functions are used in program routines to display the functional schematic of an epicyclic gear train on the computer screen. These routines are written in such a manner that other types of gear combinations can be displayed by simply adding additional modules to represent these new gear elements.